Biology

The Cell

Parts of Cell

Nucleoid Region: DNA region in prokaryotes.
Nucleolus: Makes ribosomes. Sits in nucleus, no membrane.
Peroxisomes: Collect and break down material.
Rough ER: Accept mRNA to make proteins.
Smooth ER: Detox & make lipids.
Golgi Apparatus: Modify / distribute proteins. Only in eukaryotes.
Vesicular Transport: COPII → forward | COPI ← return
Cisternal Maturation: Vesicles travel in retrograde. New Cis made. Cis/Medial/Trans/Exit
Peroxisomes: Collect and break down material.
Centrioles: 9 groups of microtubules, pull chromosomes apart.
Lysosomes: Demo & Recycling center. Made by Golgi. Single membrane.
Plasmids: In prokaryotes. Carry DNA not necessary for survival.

Bacterial Shapes

Bacilli: Rod | Cocci: Sphere | Spirilla: Spiral

Bacteria

Obligate Aerobe: Requires O₂.
Obligate Anaerobe: Dies in O₂.
Facultative Anaerobe: Toggle between Aerobic / Anaerobic.
Aerotolerant Anaerobe: Does not use O₂ but tolerates it.
Gram +: THICK peptidoglycan/lipoteichoic acid cell wall.
Gram –: THIN peptidoglycan cell wall & an outer membrane.

Eukaryote vs. Prokaryote

Eukaryote:

Prokaryote:

Miscellaneous

Prions: Infectious proteins. Trigger misfolding. α-helical → β-pleated sheets. ↓solubility.

Viroid: Plant pathogens.

Cytoskeleton

Microfilaments: Actin

Microtubules: Tubulin

Intermediate Filaments: Keratin = Vimentin; Desmin = Lamin

Tissues

Epithelia: Parenchyma (functional parts of organ).

Connective: Stroma (support, extracellular matrix). Bone, cartilage, tendon, blood.

Genetic Recombination

Transformation: Gets genetic info from environment.

Conjugation: Transfer of genetic info via conjugation bridge. F⁻ → F⁺ or Hfr → recipient

Transduction: Transfer using bacteriophage.

Transposons: Genetic info that can insert/remove themselves.

Viruses

Capsid: Protein Coat.

Envelope: Some have lipid envelope.

Virion: Individual virus particles.

Bacteriophage: Bacteria virus. Tail sheath injects DNA / RNA.

Viral Genome: May be DNA or RNA. Single or double stranded.

If Single Strand: Positive Sense: Can be translated by host cell. Negative Sense: RNA replicase must synthesize a complimentary strand, which can then be translated.

Retrovirus: Single stranded RNA. Reverse transcriptase needed to make DNA.

Bacteriophage Life Cycles: Lytic: Virions made until cell lyses. Lysogenic: Virus integrates into genome as provirus or prophage. Goes dormant until stress activates it.

Reproduction

Cell Cycle

G₁: Make mRNA and proteins to prep for mitosis

G₀: A cell will enter G₀ if it DOES NOT need to divide

G₁ Checkpoint: Cell decides if it should divide. P53 in charge

S: DNA replicated

G₂: Cell growth. Make organelles

G₂ Checkpoint: Check cell size & organelles

M: Mitosis and cytokinesis

Growth Signals

Positive Growth Signals:

  1. CDK + Cyclin create a complex
  2. Phosphorylate Rb to Rb + P
  3. Rb changes shape, releases E2F
  4. Cell division continues

Negative Growth Signals:

  1. CDK inhibitors block phosphorylation of Rb
  2. So, E2F stays attached
  3. Cell cycle halts
Sex Chromosomes

Sex determined by 23rd pair of chromosomes. XX = Female, XY = Male.

X-Linked Disorders: Males express, females can be carriers

Y-Chromosome: Little genetic info. SRY gene = “Sorry you’re a male”

Male Reproductive System

Semen: Sperm + seminal fluid.

Bulbourethral Glands: Makes viscous fluid to clean out urethra.

Seminal Vesicles & Prostate Gland: Make alkaline fluid to help sperm survive acidic environment of female reproductive tract.

SEVE(N) UP sperm pathway mnemonic

Mitosis

Prophase: DNA condenses. Centrioles migrate to opposite poles and microtubules form. Nuclear envelope disappears.

Metaphase: “Meet in the middle”. Chromosomes meet in the middle.

Anaphase: “Apart”. Sister chromatids separate and move to opposite poles.

Telophase: Chromosomes decondense. Nuclear membrane forms. Cytokinesis occurs.

Meiosis

Prophase I:

Chromosomes condense, nuclear membrane dissolves, homologous chromosomes form bivalents, crossing over occurs.

Metaphase I:

Spindle fibers from opposing centrosomes connect to bivalents (at centromeres) and align them along the middle of the cell.

Anaphase I:

Homologous pairs move to opposite poles of the cell. This is disjunction and it accounts for the Law of Segregation.

Telophase I:

Chromosomes decondense, nuclear membrane MAY reform, cell divides (cytokinesis), forms two haploid daughter cells of unequal sizes.

Prophase II:

Chromosomes condense, nuclear membrane dissolves, centrosomes move to opposite poles (perpendicular to before).

Metaphase II:

Spindle fibers from opposing centrosomes attach to chromosomes (at centromere) and align them along the cell equator.

Anaphase II:

Spindle fibers contract and separate the sister chromatids, chromatids (now called chromosomes) move to opposite poles.

Telophase II:

Chromosome decondense, nuclear membrane reforms, cells divide (cytokinesis) to form four haploid daughter cells.

Female Reproductive System

Ovaries: Have follicles that produce ova. Controlled by FSH and LH.

Oogenesis: Production of female gametes.

Estrogen: Response to FSH. Develops rep tract, thickens uterine wall.

Progesterone: Response to LH. Maintains / protects endometrium. “Estrogen establishes; progesterone protects the endometrium.”

Pathway: Egg → peritoneal sac → fallopian tube / oviduct

Gonadotropin-Releasing Hormone (GnRH)

FSH: Follicle Stimulating Hormone.
Males: Triggers spermatogenesis, stimulates Sertoli Cells.
Females: Stimulates development of ovarian follicles.

LH: Luteinizing Hormone.
Males: Causes interstitial cells to make testosterone.
Females: Induces ovulation.

The Menstrual Cycle

Embryogenesis and Development

1. Fertilization

Occurs in the Ampulla of fallopian tube.
Sperm’s Acrosomal enzymes penetrate corona radiate & zona pellucida.
Acrosomal enzymes inject pronucleus.
Cortical reaction releases Ca²⁺ which depolarizes ovum membrane and makes it impenetrable.

2. Morula

3. Blastula

4. Gastrulation

– Archenteron leads to blastopore

Ectoderm: Nervous system, skin, hair, nails, mouth, anus.
“Attract-oderm”: Skin, hair are things people are attracted to.

Mesoderm: Musculoskeletal, circulatory system, gonads, adrenal cortex.
“Move-oderm”: Involved in moving things such as muscles, RBC, steroids.

Endoderm: Endocrine glands, GI tract, respiratory tract, bronchi, bladder, stomach.
“In-oderm”: Things that are inside.

5. Neurulation

Mesoderm develops a Notochord. Notochord induces Ectoderm.

Ectoderm → Neural folds → Neural tube

Neural crest cells → Peripheral nervous system
Neural tube → Central nervous system

Stem Cells

*Adult stem cells are multipotent and require treatment w/ transcription factors

Fetal Circulation

Fetal Hemoglobin (HbF): ↑O₂ affinity than HbA
O₂ and CO₂ exchange via diffusion

Umbilical Artery: – O₂
Umbilical Vein: + O₂
PLACENTA

Twins

Fraternal = dizygotic
Identical = monozygotic

Cell Specialization

Determination: Cell commits to becoming a certain type of cell

Differentiation: Follows determination. Selectively transcribe genes appropriate for cell’s specific function

Induction

Group of cells influence the fate of nearby cells. Mediated by inducers, which are commonly growth factors.

Cell Signaling
Fetal Shunts

Nervous System

Neurons

Afferent: Ascend spinal cord

Interneurons: Between other neurons

Efferent: Exit spinal cord

Summations

Temporal: Same space / Different time

Spatial: Different space / Same time

Action Potential

Na⁺ / K⁺ Pump: 3 Na⁺ out / 2 K⁺ in

Glial Cells

White / Grey Matter

White Matter: Myelinated sheaths.

Grey Matter: Cell bodies and dendrites. Unmyelinated.

Brain: White deep / Grey outer

Spinal Cord: Grey deep / White outer

Reflex Arcs

Monosynaptic: Sensory neuron → motor neuron

Polysynaptic: Sensory → interneuron → motor

Central Nervous System

– Brain & Spinal Cord

Peripheral Nervous System

Somatic: Voluntary
Sensory: Afferent
Motor: Efferent

Autonomic:

Sympathetic

Parasympathetic

Synapse

Neurotransmitter removed from synaptic cleft via either:

Endocrine System

Peptide Hormones

Made of amino acids

  1. Cleaved from larger polypeptide
  2. Golgi modifies & activates hormone
  3. Put in vesicles released via exocytosis
  4. Polar – cannot pass through membrane, so uses extracellular receptor like GPCR

Common 2nd messengers: cAMP, Ca²⁺, IP₃

Ex: Insulin

G-Protein Coupled Receptor (GPCR)

Notes: Epinephrine is a ligand 1st messenger. At the end of the GPCR process, Phosphodiesterase deactivates cAMP and GTP hydrolyzed back to GDP.

Steroid Hormones

Ex: Estrogen / Testosterone / Cortisol

Amino Acid-Derivative Hormones

Share traits from both peptide & steroid hormones

Ex: Catecholamines use GPCR, Thyroxine bind intracellularly

Direct vs. Tropic Hormones

Direct Hormones: Act directly on target tissue/organ. Ex: Insulin.

Tropic Hormones: Require an intermediary. They only affect other endocrine tissues. Ex: GnRH and LH are both tropic.

Diabetes

Type 1: No insulin, so glucose is not able to enter cells.

Type 2: Desensitized insulin receptors. Glucose unable to enter cells.

Endocrine Organs & Hormones

Hypothalamus
Anterior Pituitary

“FLAT PEG” mnemonic

Posterior Pituitary
Pancreas
Adrenal Cortex
Adrenal Medulla

Catecholamines

Thyroid Gland
Parathyroid Glands
Gonads

Testosterone in Testes | Estrogen / Progesterone in ovaries

Pineal Gland

Melatonin controls circadian rhythm

Respiratory System

Air Pathway

Nares of nose: Nostrils

Pharynx: Food / air travels through. Air is warmed / humidified. Vibrissae filter

Larynx: Air ONLY. Epiglottis covering. Contains vocal cords

Trachea: Ciliated epithelium collect debris

Bronchi: Ciliated epithelium collect debris

Bronchioles: The smallest of the branches of the bronchi

Alveoli: Sacs where diffusion occurs. Surfactant REDUCES surface tension. Prevents collapse

Lungs

Pulmonary Veins, + O₂ ➡️ ❤️ ➡️ Pulmonary Artery, – O₂

Spirometer

Measures lung capacity
CAN NOT measure TOTAL volume

Pleurae Membranes
Inhalation
Exhalation

Active Exhalation: Internal intercostal & abdominal muscles help force air out

Protection from Pathogens
Medulla Oblongata
Bicarbonate Buffer

CO₂(g) + H₂O(l) ⇌ H₂CO₃(aq) ⇌ H⁺(aq) + HCO₃⁻(aq)

Cardiovascular System

Blood Pathway

Deoxygenated → Oxygenated

Electrical Conduction

“Stab A Big Pickle” acrostic

Blood Pressure

Systole

Ventricular contraction, AV valves close

Diastole

Ventricular relaxation, SV close, blood atria → ventricles

Normal BP: 90/60 → 120/80

Cardiac Output = Heart Rate × Stroke Volume. CO = HR × SV

Vasculature
Blood

Considered a connective tissue.

Erythrocytes (RBCs):

Hematocrit:

% of blood composed of RBCs

Leukocytes (WBCs):

Thrombocytes (Platelets):

Cell fragments. Coagulation.

Blood Type

Antigens: Surface proteins on RBCs

Rh Factor: Rh⁺ is dominant. An Rh⁻ person will only create anti-Rh antibodies after exposure to Rh⁺ blood

Blood TypeAntigens ProducedAntibodies ProducedDonate ToReceive From
A – IᴬAAnti-BA, ABA, O
B – IᴮBAnti-AB, ABB, O
AB – IᴬIᴮA and BNoneAB onlyA, B, AB, O (universal recipient)
O – iNoneAnti-A and Anti-BA, B, AB, O (universal donor)O only
Fluid Balance

Hydrostatic Pressure: Moves fluid out of the blood vessel and into the interstitial fluid around it.

Osmotic Pressure: “Sucking” pressure generated by solutes as they draw water H₂O into the bloodstream.

Oxygen: Carried by hemoglobin.

CO₂: Some carried by hemoglobin, most exist in the bloodstream as bicarbonate HCO₃⁻.

Coagulation

When the endothelial lining of a blood vessel is damaged, the collagen and tissue factor underlying the endothelial cells are exposed.

Prothrombin → Thrombin

Fibrinogen → Fibrin

Clots are broken down by Plasmin

Bicarbonate Buffer

CO₂ (g) + H₂O (l) ⇌ H₂CO₃ (aq) ⇌ H⁺ (aq) + HCO₃⁻ (aq)

Immune System

Structure

Innate Immunity:

Defenses that are always active but NON-SPECIFIC. Skin, mucus, stomach acid, tears etc.

Adaptive Immunity:

Defenses that take time to activate and are SPECIFIC to the invader.

Innate Immune System

Non-cellular innate defenses:

Cellular innate defenses:

Lymphatic System
Adaptive Immune System

Humoral Immunity:

Centers on antibody production by B-Cells. Kills antigens while they are floating around in the fluid (humoral).

Cell-Mediated (Cytotoxic) Immunity:

Centers on T-Cells. Responds to cells once they have been infected by the antigen.

Positive/Negative Selection:

Maturation of T-Cells. Facilitated by thymosin. Occurs in Thymus.

Autoimmune Conditions:

A self-antigen is recognized as foreign, and the immune system attacks normal cells

Allergic Reactions:

Nonthreatening exposures incite an inflammatory response

Immunization:

Induces active immunity (activation of B-Cells that produce antibodies)

Passive Immunity:

Transfer of antibodies to an individual. Breast milk.

Digestive System

Overview

Intracellular Digestion: The oxidation of glucose and fatty acids to make energy.

Extracellular Digestion: Process by which nutrients are obtained from food. Occurs in alimentary canal.

Mechanical Digestion: Physical breakdown of large food molecules into smaller particles.

Chemical Digestion: The enzymatic cleavage of chemical bonds such as the peptide bonds of proteins or the glycosidic bonds of starches.

Peristalsis: Rhythmic contractions of the gut tube.
↑parasympathetic nervous system
↓sympathetic nervous system

Digestive Pathway

Oral Cavity → Pharynx → Esophagus → Stomach → Small Intestine → Large Intestine → Rectum

Oral Cavity

Mastication starts the mechanical digestion. Salivary amylase and lipase start the chemical digestion of food. Food is formed into a bolus and swallowed.

Pharynx

Connects the mouth to the esophagus. The epiglottis prevents food from entering the larynx.

Esophagus

Propels food to the stomach using peristalsis. Top third has skeletal muscle and is under somatic control. Bottom third has smooth muscle, middle third has combo of both. The middle & bottom are under autonomic control.

Stomach

An acidic (pH = 2) environment. Four parts: fundus, body, antrum and pylorus. The enzyme pepsin chemically breaks down proteins.

Secretory cells that line the stomach

After processing in the stomach, food particles are now called chyme. Chyme exits through pyloric sphincter → duodenum.

Feeding Behavior Hormones
Duodenum

First part of small intestine. A basic (pH = 8.5) environment. Site of the majority of chemical digestion.

Enzymes in Duodenum

Hormones in Duodenum

Absorption and Defecation

The jejunum and ileum of the small intestine are primarily involved in absorption. The small intestine is lined with villi, which are covered with microvilli.

Vitamin Absorption:

Large Intestine – absorbs H2O and salts, forms feces

Accessory Organ

Originate from endoderm

Pancreas: Acinar Cells produce pancreatic juices that contain bicarbonate, pancreatic amylase, pancreatic peptidases, and pancreatic lipase.

Liver: Synthesizes bile, albumin and clotting factors. Process nutrients. Detox: NH3 → Urea, as well as alcohol & drugs. Liver receives blood from the abdominal portion of digestive tract via Hepatic Portal Vein.

Gallbladder: Stores & concentrates bile. CCK stimulates bile release into biliary tree, which merges with pancreatic duct.

Kidney and Skin

Excretory (urine) Pathway

Bowman’s space → proximal convoluted tubule → descending limb of the loop of Henle → ascending limb of the loop of Henle → distal convoluted tubule → collecting duct → renal pelvis → ureter → bladder → urethra

Kidney

Kidney: Contains a cortex and medulla. Produces urine which dumps into the ureter at the renal pelvis. Urine is then collected in the bladder until it is excreted through the urethra.

Nephron: Functioning unit of the kidney.

Renal Portal System: Two capillary beds in series (glomeruli & nephron). Blood flow: renal artery → afferent arterioles → glomeruli → efferent arteriole → vasa recta, which surround nephron → renal vein.

Filtration: Bowman’s capsule moves solutes from blood → filtrate. Direction and rate determined by hydrostatic and oncotic pressure differentials between the glomerulus and Bowman’s space.

Secretion: The movement of solutes from blood → filtrate anywhere other than Bowman’s capsule.

Reabsorption: The mvmt of solutes from filtrate → blood.

pH: Kidney can regulate pH with bicarbonate and H+.

Aldosterone: Steroid hormone synthesized in Adrenal Cortex in response to Angiotensin 2 or high [K+]. It is derived from cholesterol. Increases Na+ reabsorption in the distal convoluted tubule and collecting duct, thereby increasing H2O reabsorption. Result: ↑BP but no change in blood osmolarity.

ADH (Vasopressin): Peptide hormone synthesized by hypothalamus and released by posterior pituitary. ↑permeability of the collecting duct to H2O, which ↑H2O reabsorption. Result: ↑BP and ↓blood osmolarity, concentrated urine.

Nephron

Proximal Convoluted Tubule (PCT): Site of bulk reabsorption of glucose, amino acids, soluble vitamins, salt, and H2O. Site of secretion for H+, K+, NH3, and urea.

Descending Limb of the Loop of Henle: Permeable to H2O but NOT salt; therefore, as the filtrate moves into the more osmotically concentrated renal medulla, water is reabsorbed from the filtrate.

Countercurrent Multiplier System: The vasa recta and nephron flow in opposite directions, creating a countercurrent multiplier system that allows maximal reabsorption of water.

Ascending Limb of the Loop of Henle: Permeable to salt but NOT to H2O; therefore, salt is reabsorbed both passively and actively. The diluting segment is in the outer medulla; because salt is actively reabsorbed in this site, the filtrate becomes hypotonic compared to the blood.

Distal Convoluted Tubule (DCT): Responsive to aldosterone and is a site of salt reabsorption and waste product excretion, like the PCT.

Collecting Duct: Responsive to both aldosterone and ADH. Has variable permeability, which allows reabsorption of the right amount of H2O depending on the body’s needs.

Bladder

Detrusor Muscle: Muscular lining of bladder. Parasympathetic control

Internal Urethral Sphincter: Smooth muscle. Parasympathetic control

External Urethral Sphincter: Skeletal muscle. Voluntary control

Skin

Epidermis:

Langerhans Cells: Macrophages that are antigen-presenting cells in skin

Melanin: Produced by Melanocytes. Protects skin from DNA damage caused by ultraviolet radiation

Dermis: Papillary layer and reticular layer. Sensory:

Hypodermis: Fat and connective tissue. Connects skin to body

Thermo-regulation:

Muscular System

Skeletal Muscle
Smooth Muscle
Cardiac Muscle
Skeletal System

– Derived from mesoderm

Axial Skeleton: Skull, vertebral column, ribcage, hyoid bone.
Appendicular Skeleton: Bones of limbs, pectoral girdle, pelvis.
Compact Bone: Strength and density.
Spongy Bone: Lattice-like structure of bony spicules known as trabeculae. (cancellous) Cavities filled with bone marrow.
Bone Marrow: Red: Filled with hematopoietic stem cells. Yellow: Fat
Long Bones: Shafts called diaphysis that flare to form metaphyses and that terminate in epiphyses. Epiphyses contain epiphyseal (growth) plate.
Periosteum: Connective tissue that surrounds bone.
Ligaments: Attach bones to other bones.
Tendons: Attach bones to muscles.
Bone Matrix: Osteons are the chief structural unit of compact bone, consisting of concentric bone layers called lamellae, which surround a long hollow passageway, the Haversian canal. Between rings are lacunae, where osteocytes reside, which are connected with canaliculi.
Bone: Osteoblasts build bone, osteoclasts resorb bone.
Remodeling: Parathyroid Hormone: ↑resorption of bone ↑[blood Ca2+].
Vitamin D: ↑resorption of bone, ↑[blood Ca2+].
Calcitonin: ↑bone formation, ↓[Ca2+] in blood.
Cartilage: Firm & elastic. Matrix is chondrin. Secreted by chondrocytes. Avascular and is NOT innervated.
Joints: Immovable: Fused together to form sutures.
Movable: Strengthened by ligaments and contain a synovial capsule.
Synovial Fluid: Secreted by synovium, lubricates joints.
Fetus: Bones form from cartilage through endochondral ossification. Skull bones form directly from mesenchyme in intramembranous ossification.

Sarcomeres

Sarcoplasmic Reticulum: Ca2+ filled modified endoplasmic reticulum.
Sarcolemma: Cell membrane of a myocyte.
T-tubules: Connected to sarcolemma. Carry signals.

Contraction / Relaxation

Simple Twitch: Single muscle fiber responds to brief stimulus.
Frequency Summation: Addition of multiple simple twitches before the muscle has a chance to fully relax.
Oxygen Debt: Difference between O2 needed and O2 present.
Creatine Phosphate: Adds a phosphate group to ADP, forming ATP.
Myoglobin: Heme-containing protein that is a muscular oxygen reserve.

Genetics and Evolution

Definitions

Alleles: Alternative forms of a gene. Dominant allele only requires 1 copy in order to be expressed. Recessive allele requires two copies in order to be expressed.

Genotype: The combination of alleles one has at a given locus.
Homozygous: Having two of the same allele.
Heterozygous: Having two different alleles.

Phenotype: The observable manifestation of a genotype.

Dominance:
Complete: Only one dominant allele.
Codominance: More than one dominant allele.
Incomplete: No dominant alleles; heterozygotes have intermediate phenotypes.

Penetrance: The proportion of individuals carrying a particular allele that also expresses an associated phenotype.

Expressivity: The varying phenotypic outcomes of a genotype.

Genetic Leakage: Flow of genes between species via hybrid offspring.

Genetic Drift: When the composition of the gene pool changes as a result of chance.

Founder Effect: Bottlenecks that suddenly isolate a small population; inbreeding.

Taxonomic Rank: Kingdom, phylum, class, order, family, genus, species.
“King Phillip Came Over From Great Spain”

Mendel’s Laws

Law of Segregation: An organism has two alleles for each gene, which segregate during Anaphase I. Because of this, gametes carry only one allele for a trait.

Law of Independent Assortment: The inheritance of one allele does not influence the probability of inheriting a given allele for a different trait (except for linked genes).

Experiments

Experiments to support DNA as genetic material.

Nucleotide Mutations

Point Mutations: The substituting of one nucleotide for another.

Frameshift Mutations: Moving the 3 letter reading frame.

Results:
Silent: No effect on the protein.
Missense: Replace one amino acid with another.
Nonsense: A stop codon replaces an amino acid.
Insertion/Deletion: Shift in the reading frame, leading to a change in all downstream amino acids.

Chromosomal Mutations

Much larger mutations, affecting whole segments of DNA.

Results:
Deletion: A large segment of DNA is lost.
Duplication: A segment of DNA is copied multiple times.
Inversion: A segment of DNA is reversed.
Insertion: A segment of DNA is moved from one chromosome to another.
Translocation: A segment of DNA is swapped with a segment of DNA from another chromosome.

Analytical Techniques

Punnett Squares: Monohybrid cross accounts for 1 gene. Dihybrid crosses account for two genes. Sex-linked cross is linked to the X chromosome.

Recombination Frequency: The likelihood of two alleles being separated during crossing over in meiosis. Farther = ↑likely

Hardy-Weinberg Principle: If a population meets certain criteria (aimed at a lack of evolution), then the allele frequencies will remain constant.

Hardy-Weinberg Equation:
P + q = 1    (P = dominant allele freq, q = recessive allele freq)
P2 + 2Pq + q2 = 1

Evolution

Natural Selection: The mechanism for evolution is natural selection.

Modern Synthesis Model: Neo-Darwinism. Mutation and recombination are mechanisms of variation. Differential reproduction.

Inclusive Fitness: If a population meets certain criteria (aimed at a lack of evolution), then the allele frequencies will remain constant.

Punctuated Equilibrium: Considers evolution to be a very slow process with intermittent rapid bursts of evolutionary activity.

Mode of Natural Selection:
Stabilizing Selection: Keeps phenotypes in a narrow range, excluding extremes.
Directional Selection: Moves the average phenotype toward an extreme.
Disruptive Selection: Moves toward two different phenotypes at the extremes, can lead to speciation.
Adaptive Radiation: Rapid emergence of multiple species from a common ancestor, each has a niche.

Isolation: Reproductively isolated from each other by pre- or postzygotic mechanisms.

Molecular Clock Model: The degree of difference in the genome between two species is related to the amount of time since the two species broke off from a common ancestor.

Evolution Types